Characterization and physical mapping of Molluscum contagiosum virus DNA and location of a sequence capable of encoding a conserved domain of epidermal growth factor.

DNA from Molluscum contagiosum virus (MCV) isolates was analysed by restriction endonuclease cleavage, revealing two virus subtypes. Physical maps of cleavage sites for BamHI, ClaI and HindIII were constructed, and found to differ extensively between the two subtypes. MCV DNA was similar to Orthopoxvirus DNA with respect to size, terminal cross-linking and the presence of inverted terminal repetitions, but did not hybridize with vaccinia virus DNA. The genomes of the two MCV subtypes cross-hybridized and were colinear except for two small regions. There was sequence homology between DNA from corresponding map regions of the MCV subtypes but, in contrast to Orthopoxvirus DNA, no conservation of restriction sites. A synthetic oligonucleotide probe representing a conserved domain of epidermal growth factor, alpha-transforming growth factor and the vaccinia growth factor identified equivalent regions of both MCV genomes as having the potential to encode this domain. This locus is similar to the position of the vaccinia growth factor gene in vaccinia virus DNA. Thus MCV may induce epidermal cell proliferation and tumourigenesis by expression of an epidermal growth factor-like polypeptide.